Sewing thread especially bulk thread

ABSTRACT

The invention concerns a sewing thread at least the surface of which comprises a product which imparts stability to the thread and renders thread extension more difficult when the thread is sewn in. The thread is nevertheless still so elastic that it lends itself well to stitching and returns to its original state after washing.

The invention relates to a sewing thread.

BACKGROUND OF THE INVENTION

DE-A-1,265,109 teaches a sewing thread of twisted, endless, syntheticthreads onto which a dried dispersion is applied in an expensive workprocess. However, the purpose of the preparation thereby is not theconcentration of the thread circumference but that a sufficientthread-on-thread adhesion should be achieved in order to prevent ashifting of the thread and an undesired falling off of the outer threadlayers on the sewing-yarn or thread body.

The dispersion mentioned in DE-A-1,265,106 can not be washed out in theactual sense but rather must be dissolved with organic solvents.However, the use of such organic solvents contravenes the legalregulations for the treatment of textiles for human use. The organicsolvents cited in this prior publication can therefore not be used forarticles of clothing.

Many requirements are placed on a sewing yarn or thread, especially, itshould be able to be processed on machines, even on automatic sewingmachines, and meet special conditions regarding quality and softness ofa seam sewn therewith.

Traditional sewing yarns have the problem that they require aconstruction, on account of the demands placed on them, which has acertain hardness after the sewing and in the seam.

A quite essential quality feature of a seam is that the two arealstructures to be connected are joined via the seam in such a manner thatthe desired softness is achieved and a gapping of the seam as well asfraying are avoided. Only in this manner can the functional and estheticrequirements of a seam be met.

The cause for the seam wrinkling is to be found in the fact that thesewing thread is too strongly elongated or stretched when passingthrough the guides and the thread levers of the sewing machine. Afterthe sewing process the sewing thread shortens back into its initiallength (memory effect). As a result thereof, the undesired seamwrinkling occurs in the seam since the thread can only go back by thecontraction of the flexible areal structures in the seam. The backformation takes place successively as a function of the stability of theflexible areal structure, that is, of the materials to be sewn. The backformation of the thread can take place, depending on structure andcomposition, wherein one hour but possibly also not until after a fewdays. In certain instances the back formation takes place only after oneor several washing processes or cleaning processes. This depends in theparticular individual instance on within which times and by means ofwhich processes the stabilizing agents contained in the fabric can bedissolved or converted by the washing or the cleaning.

It can basically be stated that the seam wrinkling always occurs if theback formation force of the sewing thread is greater than the stabilityof the material connected by the sewing thread via the seam.

The invention has the problem of creating a sewing thread which isdesigned so that the desired seam strength is achieved by the elongationduring sewing but the restoration forces (memory effect) which otherwisetake effect within a time period can not occur.

A further essential quality feature of a seam is that it does not affectthe wearing properties and is not perceived as being very troubling. Thefact is disadvantageous in particular in the case of bathing garments,underwear, bodices and the like that the softness of these garments worndirectly on the body is lost when traditional sewing yarns are used.

The invention has the problem of preparing a bulk yarn or thread whichordinarily can not be sewn as a needle thread or can not be economicallysewn and to process it in such a manner that it can be sewn on modernsewing machines and automatic machines and that the seam strength givenby the raw material and the construction of the sewing yarn achieves theoriginal softness again even after the sewing and after a subsequentwashing.

The problem of the invention is solved by the features of claim 1.

Advantageous further developments result from the subclaims.

SUMMARY OF THE INVENTION

The special measures of the invention bring it about that practicallyany commercial sewing thread can be prepared in such a manner that theundesirable properties in and/or after a machine sewing are negated andavoided.

To this end the yarn, preferably of synthetic material, in a softstructure but also with slight ply twist and bulky, voluminousstructure, is conducted through a dispersion in such a manner that it iscoated with the dispersion in a preparative manner. This sewing threadis also optionally impregnated in such a manner with the dispersion, asa function of the structure of said thread, that any fine pores and anyinterstices are filled up therewith and in the case of multifilamentyarns the individual threads are mutually joined to each other. Thedispersion applied onto or introduced into the sewing thread issubsequently dried, which gives the sewing thread its stability.

As a result of this treatment an undesirable opening of the sewingthread during the sewing is avoided. This assures that bulk yarn can beuniversally used as needle thread and as looper thread.

If applicable, a twisting open of the individual threads of a cottonsewing yarn is prevented by the stabilizing action when sewing onautomatic machines. A more favorable seam structure and a greater seamstrength results. In addition, an uninterrupted sewing is assured inthat the sewing yarn is not subject to any delay in the longitudinalaxis ("twist accumulation") in front of the tensioning units.

A dispersion power emulsifiable in water and based on a terpolymer ofethylene, vinyl laurate and vinyl chloride has proven to be especiallyfavorable for the dispersion through which the thread is conductedduring its course of treatment.

This improves the adhesive strength, flexural tensile strength,deformability, wear resistance and the processability of the sewingthreads treated therewith.

A dispersion powder of a vinyl acetate ethylene copolymer with goodsaponification resistance and emulsifiable in water can also be used. Byvirtue of a relatively high ethylene content this resin is softer, moreelastic and slightly more tacky. This dispersion powder is particularlywell suited. Deformability and wear resistance are improved.

Moreover, both dispersion powders have a color-stabilizing property.

These dispersions can also be mixed with one another.

If necessary, an antiblocking agent can be added to these mixtures,e.g., a copolymer dispersion of acrylic acid ester with a minimumfilm-forming temperature of above 100° C. and precipitated silicic acidor pyrogenic silicic acid.

The particular mixtures can be adapted to the physical qualities of thesewing yarn by an appropriate selection.

A particular advantage of the above-mentioned dispersion powders is thefact that they can be washed out again at low wash temperatures alreadyso that after the sewing process the bulky sewing thread is againpresent in its initial state.

EXAMPLE

The process of preparing a bulky sewing thread is described by way ofexample in the following:

A synthetic, bulky sewing yarn is drawn over a special roller which dipsinto a pan with an aqueous dispersion described above. The sewing yarnis subsequently dried in a continuous process in a heating stretch andwound up. A sewing yarn treated in this manner can be readily drawn offfrom the lap or roll, sewn and subsequently returned to its original(bulky) state by means of a customary washing process.

A sewing thread treated in the manner described above also exhibits inaddition to the structural stabilization a water-repellant property anda color stabilization. Non-wash-proof colors are stabilized in such amanner by the above-described treatment that they can practically not bewashed out.

It is recommended for all plastic threads with high elongation that aplastic dispersion be selected which has a high elongation at tear afterdrying e.g. all lattices, and which can be washed out during the washingprocedure.

We claim:
 1. A sewing thread having on at least the surface thereof acoating of a dried dispersion which imparts stability to the thread andimpedes stretching thereof during sewing, but allows the thread toretain flexibility for sewing, and which can be washed out after thethread has been sewn in place comprising an emulsifiable plastic and anadditive of a polysaccharide.
 2. The sewing thread of claim 1 whereinthe emulsifiable plastic is a terpolymer of ethylene, vinyl laurate andvinyl chloride.
 3. The sewing thread of claim 2 wherein the emulsifiableplastic is vinyl acetate-ethylene copolymer.